Excess deaths among adults in the state of Santa Catarina: an ecological study during the COVID-19 pandemic, Brazil, 2020-2021

ABSTRACT Objective: to estimate excess deaths during the COVID-19 pandemic in the state of Santa Catarina and its macro-regions, Brazil, 2020-2021. Methods: this was an ecological study, using data from the Mortality Information System; excess deaths in adults were calculated by the difference between the observed number of deaths and expected number of deaths, taking into account the average of deaths that occurred between 2015 and 2019; the variables “macro-region of residence”, “quarter”, “month”, “sex” and “age group” were analyzed; data were analyzed in a descriptive manner. Results: a total of 6,315 excess deaths in 2020 and 17,391 in 2021, mostly in males (57.4%) and those aged 60 years and older (74.0%); macro-regions and periods with the greatest excess deaths were those in which there were most deaths due to COVID-19; the greatest excess deaths occurred in March 2021 (n = 4,207), with a progressive decrease until the end of the year. Conclusion: there were excess deaths in the state of Santa Catarina and in all its macro-regions during the COVID-19 pandemic.


INTRODUCTION
In 2021, Brazil became the epicenter of the COVID-19 pandemic, reaching an average of 4,000 deaths in 24 hours. 1 By the end of June 2022, Brazil recorded 669,530 deaths from COVID-19. 2 However, the data seem to underestimate the impact of COVID-19 on the country, not only because of significant underreporting, but also for the indirect consequences of the pandemic. 3,4 Problems related to resource scarcity, conflicts of interest involving political parties, lack of coordination between the spheres of the executive branch and non-compliance with social isolation measures culminated in what is considered the greatest healthcare and hospital collapse in Brazil's history. 3,5,6 Overloaded health system, delay in receiving care and difficulties in accessing services probably led to greater morbidity and mortality from other diseases, as observed in countries such as the United States and England. 3,[7][8][9] With regard to the Brazilian scenario, disorganization of services, lack of coordination among federal entities and excessive distances to be traveled when seeking care were other factors that may have contributed to an increase in morbidity and mortality. 6,10 Especially among people with chronic diseases and groups at risk from COVID-19, there was a low demand for health services as a result of more severe measures of social isolation. 3 Furthermore, it is noteworthy that the supply of essential services for other conditions and injuries has been reduced, and even interrupted in several regions, 4 impairing the continuity of care and increasing the risk of death from other causes. 3,8 Estimating the effects of the pandemic has therefore become a challenge. Studies that take into account only the notifications of deaths due to COVID-19, and disregard the indirect consequences generated by the disease, underestimate the impact of the pandemic on mortality. 11,12 Thus, the World Health Organization (WHO) recommends the calculation of excess deaths as a powerful tool to estimate the real impact of the pandemic on overall mortality among the population. [11][12][13] The objective of this study was to estimate excess deaths in the state of Santa Catarina and its macro-regions during the COVID-19 pandemic between 2020 and 2021.

METHODS
This was an ecological study conducted with the death notifications registered on the Mortality Information System (Sistema de Informações sobre Mortalidade -SIM) between January 1, 2020 and December 31, 2021, with the state of Santa Catarina as a unit of analysis. Data were accessed on January 28, 2022, via the Brazilian National Health System Information Technology Department (Departamento de Informática do Sistema Único de Saúde -DATASUS) website, (https://datasus.saude.gov.br/).

Main results
The number of deaths in the state of Santa Catarina was higher than expected in 2020 (16.3%) and 2021 (45.1%), when compared to the prepandemic years. There were excess deaths in all macroregions of the state, and it was more significant where the highest number of COVID-19 deaths occurred.

Implications for services
The excess deaths found reflect the underreporting of COVID-19 cases, in addition to lack of health care for people with other diseases. The services should expand their capacity for health care, testing, and continuity of care. Individuals from 0 to 19 years of age were excluded f rom the study, since COVID-19 manifests itself differently in children and adolescents, 14 while adults aged 20 years or older and whose death was recorded during the study period were included.

Perspectives
The expected number of deaths was calculated by the simple average of the number of deaths in the years 2015 and 2019, that is, the number of deaths in each of the five years was added (according to the location and period determined) and the result of the addition was divided by 5, according to the methodology proposed by other authors. 12,15 Excess deaths were estimated by the difference between the observed number of deaths in 2020 and 2021 and expected number of deaths for the same period. The mathematical ratio between the observed number of deaths and expected number of deaths in the period was calculated for each quarter of 2020 and 2021, according to the macro-region.
Data analysis was performed using Microsoft Off ice Excel 2016. Absolute f requencies (n), averages, standard deviation (SD) and the percentage change of the data was calculated. The percentage change of excess deaths between 2020 and 2021, in each macro-region, was calculated by using the following formula: Percentage change = (Excess deaths in 2021 -Excess deaths in 2020) x 100÷ Excess deaths in 2020 This study was not submitted for approval of a Research Ethics Committee, given that information from secondary databases, without identification of individuals, and in the public domain was used.

RESEARCH NOTE
Excess deaths and the COVID-19 pandemic

DISCUSSION
In 2020 and 2021, there were excess deaths in the state of Santa Catarina, higher in males and for the variable age, in individuals aged 60 years and older. It could be seen excess deaths and an increasing death ratio for most macro-regions of the state and periods, with the exception of the 2 nd quarter of 2020 and December 2021. The largest excess deaths occurred in the same periods and locations where there was a higher number of deaths due to COVID-19.
In a context of low testing and lack of standardization in data notification, a technical note pointed out rates of underreporting of deaths in Santa Catarina during the COVID-19 pandemic near 278%. 16 The excess deaths found in this study was 27.4% higher than the number of cumulative deaths due to COVID-19 and reported by the state. A possible explanation for this lies in the fact that excess deaths are not an indicator affected by the classification of causes of death, therefore they have not been affected by the high underreporting. 11,12 In addition, excess deaths encompass not only deaths due to COVID-19, but may also be a reflection of indirect mortality, resulting, among other factors, from health system overload that led to

RESEARCH NOTE
Excess deaths and the COVID-19 pandemic an increase in deaths from other conditions. 3 Studies show the association between higher COVID-19 morbidity and mortality and regions and locations with high population density, where there are usually higher transmission rates and lower social isolation. [17][18][19] In this study, the macro-regions with the highest demographic density were those with the highest excess deaths and most deaths due to COVID-19, in line with what is described in the literature. [17][18][19][20] Great West and Midwest and Serra, although they are locations of low population density, showed high excess deaths, especially in 2021, and possible explanations for this finding would be the intense flow of people and unfavorable sanitary conditions in meat industries in the region, which are favorable to the spread of the virus. [20][21][22][23][24] The first death due to COVID-19 in the state of Santa Catarina occurred in March 2020, when the social isolation rate reached 72.8% -probably attributed to the implementation of social distancing measures. 23,25,26 However, a study indicated inconsistency with the reality of the pandemic at the time of publication of state decrees, especially in the 2 nd half, with early flexibility and partial restrictions. At the end of the year, there was also government and media encouragement of tourism, increasing the risk of spreading the virus. 27 This scenario seems to explain the evolution of excess deaths in the state in 2020, with higher surplus in the 2 nd half of the year. 27 I n t h e s t a te o f S a n t a Ca t a ri n a , t h e stratif ication of excess deaths by sex and age showed excess deaths in males and growth with increasing age. It is commonly known that the risk of dying from COVID-19 is higher in males, associated with hormonal, immunological factors and their lower tendency to self-care. 28 The risk of death is also higher in older adults, given that, in addition to the natural consequences of aging, there is a high prevalence of comorbidities in this age group, making it more susceptible to both COVID-19 and lack of healthcare services during the pandemic. 29 As a limitation, it is noteworthy that the way to estimate the excess deaths is not among the most robust ones, although it is pointed out as a standard and effective approach. 15 Secondary databases are also directly influenced by the quality of filling out, and their heterogeneous coverage in the territory. As a potentiality, the analyzed indicator has been pointed out as one of the most important in the COVID-19 pandemic scenario, because, in addition to capturing the direct and indirect impact of mortality due to the pandemic, it is independent of testing strategies or the final classification of causes of death. [11][12][13] It can be concluded that there were excess deaths in Santa Catarina and in all its macroregions during the years 2020 and 2021, in most of the periods analyzed, higher in males and in those aged 60 years and older.